In relation to a wireless communication device using a high frequency integrated circuit, HCI (Hot Carrier Injection) degradation of a high frequency power amplifier (HPA: High-Power Amplifier) has recently become an issue with advances in miniaturization of a CMOS process.
A hot carrier degradation detection circuit using a ring oscillator has hitherto been known as a related-art technique pertinent to countermeasures against HCI degradation (for instance, Patent Literature 1). Specifically, a ring oscillator which is configured by use of a transistor that is the same as that of a main body circuit is implemented on the same chip where there is the main body circuit that is a target of detection of hot carrier degradation. As the transistor to be inspected becomes degraded, an oscillation frequency of the ring oscillator changes. Accordingly, the hot carrier degradation detection circuit is capable of detecting, based on an oscillation frequency of the ring oscillator, a degree of degradation of the transistor of the main body circuit to be detected or whether or not the end of life of the transistor is reached.
Moreover, a transmission circuit whose output signal level is variable is known (see, for instance, Patent Literature 2). Specifically, in order to inhibit degradation of power efficiency or increase of power consumption, which would otherwise occur when the output signal is small, the transmission circuit decreases a power supply voltage and operating current when the output signal is small. In contrast, when the output signal is large, the transmission circuit increases the power supply voltage and the operating current. The transmission circuit can thereby reduce power consumption adaptively to the output signal.